Absorption refrigeration



Sept. 9, 1969 J. ROEDER, JR

ABSORPTION REFRIGERATION 2 Sheets-Sheet 1 Filed April 5, 1968 .8. mm mmmm .5

I Flea P 9, 1969 J. ROEDER, JR 3,

ABSORPTION REFRIGERATION Filed April 5, 1968 I 2 Sheets-Sheet 2,Z/SOLUTION PUMP OIL LINE COOLER CHILLED WATER FLOW United States Patent3,465,541 ABSORPTION REFRIGERATION John Roeder, Jr., Benton Harbor,MiClL, assignor to Whirlpool Corporation, a corporation of DelawareFiled Apr. 5, 1968, Ser. No. 719,160 Int. Cl. F25b 15/00 US. Cl. 62476 2Claims ABSTRACT OF THE DISCLOSURE An absorption refrigeration system inwhich a pulsating oil flow is used to pump absorption liquid rich indissolved refrigerant into a generator with the system serving to cool aliquid and in which there is provided a heat exchanger for utilizingflow of the cooled liquid such as return flow from the heat exchanger ofan air conditioning system for cooling the oil of the pump so as tomaintain high efficiency.

One of the features of this invention is to provide an improved methodand apparatus for cooling the oil or similar fluid in a pulsating pumpof an absorption refrigeration system so that the pump will operate moreefliciently in forcing absorption liquid rich in dissolved refrigerantinto a generator where refrigerant gas is driven from the liquid.

Other features and advantages of the invention will be apparent from thefollowing description of one embodiment thereof taken in conjunctionwith the accompanying drawings. Of the drawings:

FIGURE 1 is a semi-diagrammatic representation of a liquid-gasrefrigeration system having parts thereof embodying the invention andwith certain parts shown in section and others in side elevation.

FIGURE 2 is a fragmentary perspective view of the oil heat exchangerportion of the system.

FIGURE 3 is a fragmentary side elevational view partially in sectionillustrating the pump and the oil cooling portion of the system.

In the system shown in the drawings there is provided a generator-refluxcondenser 10. Heat is applied to the bottom 11 of the generator in thecustomary manner as by a gas flame (not shown) with the result thatgaseous refrigerant is driven off and collects in the top space 12 ofthe generator from where it is directed through a pipe 13 and from therethrough twosmaller parallel pipes 14 and 15 with the pipe 14 leading tothe entrance of a coil 16 of a bank of coils 17 arranged adjacent eachother. The other and parallel pipe 15 leads to the entrance of anothercoil 18 in this bank. The bank 17 of coils which in the illustratedembodiment is completed by still another coil 19 operates as a combinedabsorber and condenser.

The absorber portion of the bank will be explained hereinafter. Thecondenser portion receives the gaseous refrigerant which is in heatedcondition from the generator space 12 by way of the large pipe 13 andtwo smaller pipes 14 and 15 into the closely adjacent parallel coils 16and 18. As the gaseous refrigerant becomes reduced in volume due to itscondensing to a liquid the refrigerant at a lower point in the coil 16is conveyed to a portion of the outer coil 18 by means of a branch line20. After condensation is complete in the coil 18 the liquid refrigerantthen passes from the coil 18 by means of a pipe 21 into a heat exchanger22. This heat exchanger is disclosed in the copending application ofJohn Roeder, Jr., Ser. No. 498,235, filed Oct. 20, 1965, and assigned tothe same assignee as the present application.

The liquid refrigerant from the pipe 21 passes through a helical coil 23in the heat exchanger 22 by way of a short 3,465,541 Patented Sept. 9,1969 capillary tube 24 at the entrance to the helical coil 23. Uponleaving the coil 23 the liquid refrigerant then passes through anothercapillary tube 25 into a coil evaporator 26 surrounded by a container 27for a heat exchange liquid. This heat exchange liquid flows into thecontainer 27 -by way of a circulatory pipe 29 as indicated by the arrow28, is chilled therein and then flows from the container 27 by way ofthe pipe 29 as indicated by the arrow 30. In this embodiment the chilledliquid flowing through the pipe 29 is used to air condition a building(not shown) in the customary manner.

Gaseous refrigerant from the evaporator 26 is conducted by way of a pipe31 to the interior of the heat exchanger 22 surrounding the helical coil23. From the interior of the exchanger 22 the gaseous refrigerant whichhas precooled the entering liquid refrigerant in the coil 23 is conveyedby a pipe 32 to the top of a vertical absorberheat exchanger 33.

In the absorber-heat exchanger 33 a bulkhead cross plate 34 defines anupper section 35 into which the gaseous refrigerant flows from the pipe32. Extending downwardly within the absorber 33 from the section 35 is avertical tube 36. This tube which extends downwardly to adjacent thebottom 37 of the absorber 33 has surrounding it a helical coil 38 forconveying absorption liquid rich in dissolved refrigerant to thegenerator 10.

Positioned above the topmost turn of the helical coil 38 is adistributing cup 39 for weak liquid that is received from the generator10 through a pipe 40 and capillary 41. From the cup 39 weak liquid flowsthrough a plurality of spaced exit nozzles 42 onto the topmost end ofthe helical coil 38 and over the coil down to the bottom 37 forcountercurrent absorption flow with refrigerant gas rising in the spacebetween the tube 36 and the heat exchanger 33 sothat the gas is absorbedin this downflowing liquid. As indicated, the coil 38 is spaced from thewall of the absorber to provide a space 43 and is also spaced from thetube 36 to provide the space 44. In the preferred construction thespaces 43 and 44 are of substantially equal Width. With this arrangementthe rising refrigerant gas passes on both the inner and outer sides ofthe coil 38 while it is being absorbed in the liquid that is flowingdown over the outer surfaces of the coil 38.

The absorption liquid and a certain amount of the gaseous refrigerantentrained therein are forced upwardly by internal pressure through theplurality of pipes 45 which have their entrance ends adjacent the bottom37 of the vertical absorber-heat exchanger 33.

The exit pipes 45 for the upward flow of absorption liquid and somegaseous refrigerant pass upwardly through the internal tube 36 so thatthese pipes are in heat exchange contact with the cold refrigerant gasflowing down the tube 36. Because the pipes 45 are of metal which is aheat conducting material the absorption liquid in these pipes isprecooled.

The coil 38 through which flows rich liquid on its way to the generatorby way of the pipe 46 is supplied with rich liquid by a pipe 47 whichalso extends downwardly through the tube 36 in heat exchange relationwith downwardly flowing gaseous refrigerant therein.

The plurality of pipes 45 for the absorption liquid and unabsorbedrefrigerant gas, here shown as four in numtions 76 and 77 thereof. Theabsorber sections 50 and 51 of the first coil 19 in the bank of coils17. In these sections there is a further absorption of refrigerant gasinto the liquid. The bottoms of the two sections 48 and 49 are joined bya branched pipe 52 for flow into an absorption section 53 of the firstcoil 16 beneath the condenser portions 76 and 77 thereof. The absorbersections 50 and 51 of the first coil 19 are joined by a similar branchedpipe 54 for flow to the top of an absorber section 55 at the bottom ofthe second coil 16. The bottoms of the absorber sections 53 and 55 arejoined by a branch pipe 56 for flow into the bottom absorber section 57of the third coil 18 which is the outer coil which is contacted first bythe cooling air flow indicated by the arrows 58.

In the bank of coils 17 there is achieved final absorption of gaseousrefrigerant into the absorber liquid and condensing of gaseousrefrigerant to liquid refrigerant with individual coils being arrangedin finned sections with each section operating as a heat exchanger.Furthermore, in the third coil 18 where cooling by the air flow 58 is ata maximum the now liquid refrigerant is conveyed from the condenser andthe rich absorption liquid is directed by way of the pipe 59 toward thegenerator 10.

In order to keep the absorber spaces 43 and 44 in the absorber-heatexchanger 33 free from substantial amounts of noncondesible gases whichwould interfere with absorption, the top of the absorber-heat exchanger33 beneath the top plate 34 is vented by means of a conduit 60 into thespace 34. The upper exit end of this conduit is restricted and issurrounded by the gaseous refrigerant pipe 32 at its exit into the space35 so that the flowing gaseous refrigerant sets up a vacuum in theconduit 60 to draw non-condensible gases from the top of theabsorber-heat exchanger 33. By drawing these gases from the absorber 33they cannot then interfere with the absorption of refrigerant into theliquid.

The rich absorption liquid pipe 59 empties into the top of a reservoir61 and collects in the space 62 above a plate 63 in the reservoir 61.This liquid then overflows into the top of a vertical pipe 64 for flowto the space 65 beneath the plate 63. The rich absorption liquid fromthis space 65 is pumped by means of a diaphragm pump 66 into the highpressure side of the system.

This is accomplished by providing a surge tank 67 within the space 62with a vertical pipe 68 extending upwardly through the dividing plate 63to adjacent the top of the surge tank 67. The bottom of this pipe 68 isprovided with a check valve 69 which permits flow only upwardly into thepipe 68 and this pipe is also provided with a second check valve 70above the first valve 69 that also permits flow only in an upwarddirection. The portion 71 of pipe 72 between these valves is connectedby a short pipe 73 to the space 74 that communicates with the diaphragmpump 66.

The plate 63 which defines the bottom of the space 62 is provided with asmall orifice 85 for metering rich solution from chamber 62 into thespace 65. In addition to this orifice the previously described pipe 64has its lower opening beneath the plate 63 and into the chamber 65.During operation the orifice 85 permits rich solution to pass fromchamber 62 to the lower space 65 but the main flow is into the top ofthe pipe 64 and downwardly therethrough. During periods of shut-down thesolution trapped in chamber 62 drains slowly through orifice 85 toprovide suflicient liquid in the space 65 for the proper operation ofthe solution pump and the immediate supply of liquid to the generator atstart-up.

The lower ends of orifice 85 and pipe 64 are spaced below plate 63 sothat the space 65 does not become completely filled with solution duringthese shut-down periods.

As stated earlier, the top of the vertical pipe 68 is located within thesurge tank 67 adjacent the upper end thereof. Leading from adjacent thebottom of this surge tank is a rich liquid pipe 75 that leads to a coil76 in the heated vapor space 12 at the top of the generator 10 and fromthere to the previously mentioned pipe 47 leading to the absorber-heatexchanger 33.

A reservoir 61-pump 66 system of this same general type is disclosed andclaimed in Patent No. 3,357,203, issued Dec. 12, 1967, and assigned tothe same assignee as the present application.

The surge tank 67 in the rich liquid pumping system trapsnon-condensible gases at the top of the surge tank to function ascompressible means therein that aid in absorbing pressure pulsations ofthe diaphragm pump 66. As is customary with pumps of this type hydraulicpressure in the oil line 78 pulsates back and forth as indicated by thedouble-headed arrow 79, but because of the provision of the one-wayvalves 69 and the direction of the liquid acted upon by the pump 66 isonly upwardly into the surge tank 67 and from there up through the pipe75.

The surge tank 67, therefore, has a variety of functions. It reduceswater hammer effects normally set up by the pulsating pump 66, itsmoothes the discharge pressure of the rich liquid through the pipe tothe high pressure portions of the system and collects non-condensiblegases and utilizes them as a resultant cushion. In addition, the surgetank acts as a gas trap with liquid at the bottom of the tank 67covering the inlet to the pipe 75 when the system is not operating,thereby maintaining the system substantially free from undesirablenon-condensible gases.

The diaphragm pump 66 is operated by pulsating oil pressure in the pipe78 as indicated by the arrow 79. Such a system is shown in FIGURE 2 andsemi-digrammatically in FIGURE 3. As is shown here, an oil pump 80 of acustomary type applies pulsating pressure to oil in a line 81 that leadsto a control heat exchanger 82 which is in heat exchange relationshipsurrounding the chilled liquid circulating pipe 29 leading back to theevaporator 26 as indiacted by the arrow 28 in FIGURE 1. From the heatexchanger 82 the oil line 78 leads to an operating chamber 83 beneaththe diaphragm 84 of the pump 66.

With this arrangement the cool circulating liquid on its return to theevaporator container 27 to be again chilled by the evaporator 26 is usedto cool the hydraulic liquid that operates the diaphragm pump. Thiscooling of the hydraulic liquid has been found to be very beneficial inpreventing substantial oil slippage in the pump 80 which occurs when theoil temperature becomes excessive such as above F. Such an elevated oiltemperature is frequently achieved when the ambient temperature is highand is particularly undersirable, since in times of high ambienttemperatures high pump efliciency is needed most.

In addition the heat exchange cooling of the hydraulic oil greatlyreduces or eliminates the problem of flashing of the oil at thediaphragm 84 of the pump. This flashing may be not only of the oil onthe working or lower side of the diaphragm in the embodiment illustratedbut flashing may also occur in the refrigerant such as ammonia on thepumped fluid side of the diaphragm or the upper side in the embodimentillustrated. This flashing occurs on the suction stroke because of thereduced pressure at the diaphragm and is particularly noticeable atelevated temperatures. Such flashing reduces the efficiency of the pumpbecause the pockets of gas formed by the flashing must be compressed andrecondensed on the power stroke of the pump before efficient work can beaccomplished.

Having described my invention as related to the embodiment shown in theaccompanying drawings, it is my intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but rather be construed broadly within its spirit and scopeas set out in the accompanying claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. two-pressure absorption refrigeration system, comprising:

an evaporator on the lower pressure side of said system in which liquidrefrigerant is evaporated to produce cooling;

a generator on the higher pressure side of said system in whichrefrigerant gas is expelled from absorption liquid rich in dissolvedrefrigerant;

liquid conduit means for conveying said rich liquid to said higherpressure side generator from the lower pressure side of said system;

5 6 a pressure applying pump means operatively associated ReferencesCited with said conduit means for causing said conveying, UNITED STATESPATENTS sald pump means comprlslng a hydraulic llquld supply; and meansassociated with said evaporator for 2,684,579 7/1954 Hieatt t a1. 62468cooling said hydraulic liquid for maintaining the 2,963,886 12/1960Palmatier 62468 eflicierlcy of said pump means. 5 3,357,203 12/ 1967Briggs 62489 2. The absorption refrigeration system of claim 1 whereinsaid means associated with said evaporator in- LLOYD L. KING, PrimaryExaminer cludes a circulating chilled liquid system in which said liquidis chilled by said evaporator, and a heat exchanger for cooling saidhydraulic liquid from said chilled liquid 62487, 489 line.

US. Cl. X.R.

